My preferred answer, based on what you have told us, is in the question:
Use an "Event". http://msdn.microsoft.com/en-us/library/ms682396(VS.85).aspx One application creates the event, the other obtains a handle to the same named event (whichever one starts first Creates it, the other Open's it, so both apps have to deal with either getting first bite of the cherry or coming runner up J) The key is in the two apps agreeing on the name of the event object so that they are referring to the same thing - I forget the details of achieving this and leave that research as an exercise for the reader. J App B can then WaitFor on the event until app A signals it. You may need a similar mechanism for communication of B's completion of processing too. Hope that helps. From: delphi-boun...@delphi.org.nz [mailto:delphi-boun...@delphi.org.nz] On Behalf Of John Bird Sent: Wednesday, 18 August 2010 16:43 To: NZ Borland Developers Group - Delphi List Subject: [DUG] Sending notification between programs Which way would you favour to do the following ? I have two Delphi programs (A and B) that I will pass data from A to B - I will probably use a file to put the data in because its quite structured. B will sleep on a timer loop until this something is triggered. What I want to do is send a simple notification from program A to B that there is something to do - i.e. trigger an event in B to wake and do something to process this. There are various ways I could communicate this notification 1 - Has to add minimal overhead of size and processing to programs A and B 2 - A can tolerate B not responding immediately without freezing but preferably will know The ways I have considered to be candidates are a - Windows messaging b - TCP/IP Indy (which could send the data too. (adds complexity of needs to be done in a thread to not affect the main program A) c - make program B a DLL d - Roll my own - make a timer in B which polls for for some condition and otherwise continues to sleep e - something else. Kindly share your favoured options how you might do this. John
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